Changing Trends in Chickenpox – Pregnant Women and Prevention with Vaccine A A Gershon (USA) © 2000 The International Herp...
Varicella zoster virus: risks during pregnancy <ul><li>Varicella zoster virus (VZV) is 25 times more serious in adults tha...
<ul><li>Congenital varicella syndrome: </li></ul><ul><ul><li>involvement of skin, limbs, eyes, brain, growth </li></ul></u...
Infant with fatal varicella
Infant with congential varicella syndrome
Infant with early zoster
Varicella susceptibility by age, USA 1988–1994 <ul><li>Age (years) Susceptibility (%) </li></ul><ul><li>  6–11 14 </li></u...
Live attenuated varicella vaccine <ul><li>Developed by Takahashi over 25 years ago </li></ul><ul><li>Oka strain produced b...
Risk to pregnant woman if susceptible child in family is vaccinated/not vaccinated <ul><li>Wild VZV (%)   Vaccine (%) </li...
Risk to infant if susceptible child in family is vaccinated <ul><li>Assumes mother is susceptible </li></ul><ul><li>Assume...
Safety and efficacy of varicella vaccine in  adults and children <ul><li>Adults require 2 doses to achieve >90% seroconver...
Varicella vaccine: case-control efficacy study <ul><li>4 private practices in New Haven, CT, USA </li></ul><ul><li>83 case...
Leukaemic child with breakthrough varicella
Vaccination of health care workers against chickenpox <ul><li>120 healthy adults, 19–45 years old </li></ul><ul><li>Vaccin...
Zoster in immunocompromised vaccinees  after immunization Years after Vaccinees (%) Controls (%) immunization Leukaemia (T...
Varicella vaccine in USA CDC Draft: healthy people, 2010 goals <ul><li>Reduce indigenous varicella in USA by 90% </li></ul...
Varicella vaccine: persistence of immunity <ul><li>Duration of immunity never known with new vaccine </li></ul><ul><li>In ...
Varicella vaccine: persistence of immunity <ul><li>No apparent increase in rate or severity of breakthrough disease with t...
VZV: practical aspects for pregnant women <ul><li>Identification of varicella susceptibles </li></ul><ul><li>History of di...
VZV: practical aspects for pregnant women <ul><li>VZIG for pregnant susceptible women with close </li></ul><ul><li>exposur...
VZV: practical aspects for pregnant women <ul><li>Immunization of healthy, non-pregnant </li></ul><ul><li>varicella suscep...
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Changes Trend in Chickenpox - Pregnant women and prevention with vaccine Changes Trend in Chickenpox - Pregnant women and prevention with vaccine

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Changes Trend in Chickenpox - Pregnant women and prevention with vaccine Changes Trend in Chickenpox - Pregnant women and prevention with vaccine

  1. 1. Changing Trends in Chickenpox – Pregnant Women and Prevention with Vaccine A A Gershon (USA) © 2000 The International Herpes Management Forum, all rights reserved.
  2. 2. Varicella zoster virus: risks during pregnancy <ul><li>Varicella zoster virus (VZV) is 25 times more serious in adults than in children: </li></ul><ul><ul><li>50 annual deaths in adults in the USA </li></ul></ul><ul><li>No apparent risk of spontaneous abortion </li></ul><ul><li>Maternal risk probably highest in 3rd trimester: </li></ul><ul><ul><li>reports of pneumonia requiring antiviral therapy </li></ul></ul><ul><ul><li>reports of fatalities </li></ul></ul><ul><li>Risk to fetus and newborn due to maternal viraemia </li></ul><ul><li>Zoster not a problem (secondary infection) </li></ul><ul><li>Many susceptible adults in countries with tropical climate </li></ul>
  3. 3. <ul><li>Congenital varicella syndrome: </li></ul><ul><ul><li>involvement of skin, limbs, eyes, brain, growth </li></ul></ul><ul><ul><li>pathogenesis unclear – possibly VZV reactivation in utero </li></ul></ul><ul><ul><li>2% of offspring affected when maternal varicella occurs at Weeks 8–20 </li></ul></ul><ul><ul><li>diagnosis difficult: PCR, ultrasound </li></ul></ul><ul><ul><li>no therapy, counselling difficult </li></ul></ul><ul><li>Severe disseminated infection of the newborn </li></ul><ul><ul><li>babies born 4 days or less after onset of maternal varicella </li></ul></ul><ul><ul><li>can be modified with VZIG given at birth </li></ul></ul><ul><li>Asymptomatic at birth but early development of zoster </li></ul>
  4. 4. Infant with fatal varicella
  5. 5. Infant with congential varicella syndrome
  6. 6. Infant with early zoster
  7. 7. Varicella susceptibility by age, USA 1988–1994 <ul><li>Age (years) Susceptibility (%) </li></ul><ul><li> 6–11 14 </li></ul><ul><li> 12–19 6.8 </li></ul><ul><li> 20–29 4.5 </li></ul><ul><li> 30–39 1.1 </li></ul><ul><li> >40 1.3 </li></ul>
  8. 8. Live attenuated varicella vaccine <ul><li>Developed by Takahashi over 25 years ago </li></ul><ul><li>Oka strain produced by attenuation during cell passage </li></ul><ul><li>Licensed for use in Japan and Korea 1989 </li></ul><ul><li>Licensed in USA in 1995 for healthy susceptibles aged >1 year </li></ul><ul><li>Over 15 million doses distributed in USA: </li></ul><ul><ul><li>3 instances of transmission (mild contact cases) </li></ul></ul><ul><li>Contraindicated during pregnancy: </li></ul><ul><ul><li>365 inadvertently vaccinated, no congenital varicella (CDC) </li></ul></ul><ul><ul><li>recommended for susceptible children of pregnant women </li></ul></ul>
  9. 9. Risk to pregnant woman if susceptible child in family is vaccinated/not vaccinated <ul><li>Wild VZV (%) Vaccine (%) </li></ul><ul><li>Virus 7 100 </li></ul><ul><li>Rash 100 5 </li></ul><ul><li>Transmission 80 <1 </li></ul><ul><li>Risk to mother <0.5 6 </li></ul>
  10. 10. Risk to infant if susceptible child in family is vaccinated <ul><li>Assumes mother is susceptible </li></ul><ul><li>Assumes one child (double risk for two) </li></ul><ul><li>Assumes 2% risk of congenital syndrome </li></ul><ul><li>Assumes Oka causes congenital syndrome like wild type </li></ul><ul><li>Assumes Oka crosses placenta like wild type: </li></ul><ul><ul><li>no documented viraemia in healthy vaccinees </li></ul></ul><ul><li>Predict significantly lower risk to mother and fetus </li></ul>
  11. 11. Safety and efficacy of varicella vaccine in adults and children <ul><li>Adults require 2 doses to achieve >90% seroconversion </li></ul><ul><li>Vaccine extremely safe in children and adults: </li></ul><ul><ul><li>rash in first 2 weeks may be wild type VZV </li></ul></ul><ul><ul><li>5–10% mild rash 1–6 weeks (mean 4) after immunization </li></ul></ul><ul><ul><li>rare temporal association with severe adverse events (e.g. pneumonia, anaphylaxis, thrombocytopaenia) </li></ul></ul><ul><li>75–85% protection after household exposure to varicella </li></ul><ul><li>Rare zoster in USA vaccinees: </li></ul><ul><ul><li><30 cases, 2/3 Oka, 1/3 wild type VZV </li></ul></ul><ul><li>Waning immunity not a significant problem </li></ul>
  12. 12. Varicella vaccine: case-control efficacy study <ul><li>4 private practices in New Haven, CT, USA </li></ul><ul><li>83 case-control groups </li></ul><ul><li>Varicella group: 14% vaccinated </li></ul><ul><li>Control group: 48% vaccinated </li></ul><ul><li>85% efficacy after 2 years of 5-year study </li></ul>
  13. 13. Leukaemic child with breakthrough varicella
  14. 14. Vaccination of health care workers against chickenpox <ul><li>120 healthy adults, 19–45 years old </li></ul><ul><li>Vaccinated in USA 1979–1997 </li></ul><ul><li>Most received 2 doses, 1–2 months apart </li></ul><ul><li>Average follow-up 5 years (range 1–20 years) </li></ul><ul><li>12 cases break-through varicella (10%): </li></ul><ul><ul><li>average 40 vesicles (<10 times expected) </li></ul></ul><ul><ul><li>0.5–7 years after vaccination </li></ul></ul><ul><ul><li>Disease occurred in vaccinees who lost detectable antibodies to VZV </li></ul></ul>
  15. 15. Zoster in immunocompromised vaccinees after immunization Years after Vaccinees (%) Controls (%) immunization Leukaemia (Takahashi) 6 6 19 Leukaemia (Brunell) 6 0 21 Leukaemia (Hardy) 10 2 16 Renal transplant (Broyer) 10 7 13
  16. 16. Varicella vaccine in USA CDC Draft: healthy people, 2010 goals <ul><li>Reduce indigenous varicella in USA by 90% </li></ul><ul><li>Vaccine coverage >90% among children (19–35 months): </li></ul><ul><ul><li>national level and all 50 states </li></ul></ul><ul><li>Vaccine coverage >95% for children at school entry </li></ul><ul><li>Modelling indicates that fewer overall cases of varicella increased average age of onset: </li></ul><ul><ul><li>however, as for measles in the USA, there will be fewer cases of adult varicella </li></ul></ul><ul><li>There are already changes in epidemiology of illness in children </li></ul>
  17. 17. Varicella vaccine: persistence of immunity <ul><li>Duration of immunity never known with new vaccine </li></ul><ul><li>In USA, 5–10 year follow-up of >500 immunized healthy children: </li></ul><ul><ul><li>over 90% remain seropositive </li></ul></ul><ul><li>20-year follow-up of 26 Japanese vaccinees: </li></ul><ul><ul><li>2 developed mild break-through infections, 100% seropositive </li></ul></ul>
  18. 18. Varicella vaccine: persistence of immunity <ul><li>No apparent increase in rate or severity of breakthrough disease with time: </li></ul><ul><ul><li>children (Johnson et al ) </li></ul></ul><ul><ul><li>adults (Saiman et al ) </li></ul></ul><ul><li>Effect on varicella and zoster in absence of boosting from natural disease will require further study </li></ul>
  19. 19. VZV: practical aspects for pregnant women <ul><li>Identification of varicella susceptibles </li></ul><ul><li>History of disease >95% reliable </li></ul><ul><li>ELISA tests approximately 75% accurate: </li></ul><ul><ul><li>false negatives > false positives </li></ul></ul><ul><ul><li>testing costs vary from US$1–40 per assay </li></ul></ul><ul><ul><li>other antibody tests limited availability (LA, FAMA) </li></ul></ul>
  20. 20. VZV: practical aspects for pregnant women <ul><li>VZIG for pregnant susceptible women with close </li></ul><ul><li>exposures and selected offspring </li></ul><ul><li>To protect mother (impact on congenital syndrome?) </li></ul><ul><li>At birth if mother has varicella onset <5 days before delivery </li></ul><ul><ul><li>or within 48 hours post-delivery </li></ul></ul>
  21. 21. VZV: practical aspects for pregnant women <ul><li>Immunization of healthy, non-pregnant </li></ul><ul><li>varicella susceptibles in household </li></ul><ul><li>Pre-exposure (preferable) or post-exposure vaccination </li></ul>

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